Networks uncover hidden lexical borrowing in Indo-European language evolution

Abstract

Language evolution is traditionally described in terms of family trees with ancestral languages splitting into descendent languages. However, it has long been recognized that language evolution also entails horizontal components, most commonly through lexical borrowing. For example, the English language was heavily influenced by Old Norse and Old French; eight per cent of its basic vocabulary is borrowed. Borrowing is a distinctly non-tree-like process—akin to horizontal gene transfer in genome evolution—that cannot be recovered by phylogenetic trees. Here, we infer the frequency of hidden borrowing among 2346 cognates (etymologically related words) of basic vocabulary distributed across 84 Indo-European languages. The dataset includes 124 (5%) known borrowings. Applying the uniformitarian principle to inventory dynamics in past and present basic vocabularies, we find that 1373 (61%) of the cognates have been affected by borrowing during their history. Our approach correctly identified 117 (94%) known borrowings. Reconstructed phylogenetic networks that capture both vertical and horizontal components of evolutionary history reveal that, on average, eight per cent of the words of basic vocabulary in each Indo-European language were involved in borrowing during evolution. Basic vocabulary is often assumed to be relatively resistant to borrowing. Our results indicate that the impact of borrowing is far more widespread than previously thought.

Punctuated equilibrium in the large-scale evolution of programming languages

“…The absence of a 'genome' is a great challenge, since it prevents us from exploiting some type of metric defining the distance among inventions. Only human languages were allowed to systematically reconstruct phylogenies while taking into account lateral transfer [13]. In this paper, we have shown that a simple network approach can reconstruct phylogenetic trees from existing databases that include information on who influenced whom in a given branch of technological development.…”

“…Human languages are a clear exception to the rule, since it is possible to properly define distances among words or other components and reconstruct their evolutionary record [11]. As occurs with microbial species [12], languages also display high levels of horizontal transfer, which can be treated with the appropriate tools [13]. Surprisingly, almost no attention has been dedicated to the evolution of information technology, despite its well-preserved fossil record [6,14,15].…”

Correlational Studies in Typological and Historical Linguistics

“…It has been used to estimate the date of protolanguage splits (e.g., Gray & Atkinson 2003, Atkinson et al 2005 and to estimate rates of change (Pagel et al 2007, Atkinson et al 2008, Dediu 2011) and rates of geographical spread (Bouckaert et al 2012). Other important questions that can be dealt with in this way are those related to correlated evolution ) and the relative importance of vertical inheritance and language contact (Currie et al 2010, Nelson-Sathi et al 2010.…”

Universal typological dependencies should be detectable in the history of language families

“…Third, treating phylogeny as the clear structural scaffold against which horizontal transmission can be detected, a strategy criticised in a number of the commentaries, is justified by the state of the art; we have a science of phylogenetic inheritance, but only the glimmerings of a science of lateral transmission (e.g. Gray et al 2011, Nelson-Sathi et al 2011.…”